Hello Rob
nice one! As this letter to Wurttemberg was dispatched via Bade, Bade got 6 Kreuzer from Switzerland and Switzerland kept 10 Rappen for their 1st Rayon.
If the Swiss hat sent it via lake Constance to Friedrichshafen (Wurttemberg), what was regular, Wurttemberg had got 6 Kreuzer from the Swiss postoffice.